This invention relates to a device for adjusting the loop density in a circular knitting machine, in particular a hose knitting machine.
The above adjustment, as is known, is effected by shifting the needle cylinder vertically with respect to the plane of formation of the loops or to the cam assemblies, so that shorter or longer loops can be formed. The cylinder, which can be shifted axially with respect to the cylinder holder, bears through load bearing rods onto a thrust bearing, in turn supported by a forked end of a lever. This lever is pivoted centrally to the stationary structure of the machine, and has an opposed end in abutment relationship with the middle portion of an adjustment rod, the latter being pivoted with one end onto the machine stationary structure and abutting with the other end a stationary portion of the machine. The rod can be displaced from its inoperative or home position by the action of cams provided on the machine main drum, which through small control levers, can act on the free end of respective levers, which will shift accordingly, and as required, the adjustment rod out of its home position. Thus, the adjustment of the needle cylinder height, and hence of the loop density, is accomplished during the progressive rotation of the main drum.
Such prior devices have the disadvantage of a complex mechanical construction, which requires a high number of levers, and of consequence considerable space in the machine and over the main drum. Moreover, the operator or erector must display remarkable skill and sensitivity in tuning the machine, in that he has to manipulate a high number of adjusting screws, which may readily result in an inaccurate adjustment. Owing to machining tolerances and the multiple levers interposed between the main drum and cylinder, such devices are unsuitable for standard series tuning, and each machine must be tuned on an individual basis.